My girlfriend changed the batteries on our thermostat this morning and ever since the AC just continues to run even when the thermostat is set to off. I pulled the fuse on the outside by the AC until I can figure out how to fix it. Any ideas?

biggles

07-21-2012 10:58 AM

program might of went to default to run on one setting...but should shut off it switched at the subbase...unless she hit override.on that subbase do you have a wire going to C terminal?just wondering if the battery runs the stat if no C wire it might...if it is digital and show system OFF fan OFF and it still runs something is up..pulling the disconnect kills the line power but the contactor is controlled from the transformer in the air handler...do you have a solid state control module in the air handler

turnermech

07-21-2012 02:06 PM

What was the brand and type of thermostat? Did the thermostat have to be removed from its sub-base to change the batteries or was there a batteries cover on the front? Is it just the outside unit that continues to run or inside unit or both?

The off setting should override the program of the thermostat. If you had to remove the thermostat from the base the connecting pin or the wiring may have been compromised Try to repeat the procedure you did while initially changing the batteries and look for any obvious things out of place. I the batteries are in the front that should not be the case. Where these new batteries?

This could also be a coincidence and be another problem not related to the batteries. Another thought are you allowing at least 5 minutes to pass for any changes to take place once you do anything at the thermostat. A lot of digital thermostats don't respond immediate after changes to the settings. I have seen people think they have a problem when they just are not allowing enough time for the thermostat to respond before pushing another button and resetting the time delay.

RyanNirg

07-21-2012 02:30 PM

I took it apart again, this time paying close attention to the pins and wires. Everything looked good until I gave each wire a little tug and one of them came right out. So I reattached it and now everything functions properly. Easy fix, thanks for the input!